I have 99 Seville STS. 148,000 miles. Very nice and well maintained. Only code is B1343-Air Inlet Door Movement. I replaced busted Pressure Tank with a brand new one. Now I'm getting "Check Coolant Level" on DIC. Coolant level is good. So, I changed the sensor to the old one. I'm still getting "Check Coolant Level". Voltage is good. 11 volts with key on and goes up to 13 when I start engine. I disconnected battery cables to reset everything. Still getting "Check Coolant Level". Float seems to work properly. I'm thinking defective part maybe? Any ideas?